In my session in Professor Lee's class, one of the things that showed up on several slips of paper as a block to people being productive with schoolwork was TV.
I'm afraid none of the students came up with anything for defeating the power of the device that brings us Grey's Anatomy, Battlestar Galactica, Holmes on Homes, Dr. Phil, Little People - Big World and all those other diversions. So I tossed out the only way I have found to prevent myself from turning on the TV. The class did not seem to buy it, but it sometimes works for me so here it is:
I go online and read the TV listings.
I think it works because it confirms there is really nothing on that I want to watch. When I flip through the channels with the remote, I always have to go around a few times to make sure that I didn't miss something that was on a commercial break and then I might as well see if anything good came on at the half-hour. Before long several hours have passed and I'll have watched parts of fifteen programs that I didn't enjoy.
[I thought I learned this tip on Unsorted Lifehacks page on Merlin Mann's 43 Folders wiki, but as I write this, the tip is not there. No problem, it's a wiki, so I'll just add it.]
[This is the link that gets me to my TV listings, I don't know what it'll do for you. I like this one because it is easy to set the time and day you want to see the listings for and if you play with your settings you can get all of your channels on the page.]